The invention relates to a method of fabricating a flash memory device and, more particularly, to a method of fabricating a flash memory device, which can easily form a floating gate by improving the patterning process of the floating gate.
As the degree of integration of semiconductor memory devices increases, not only the width of gates, but also the distance between the gates is narrowed. To form such micro patterns, processes for forming such semiconductor memory devices have necessarily been improved. A method for forming a flash memory device is described below by way of example.
A tunnel dielectric layer is formed over a semiconductor substrate (a gate dielectric layer is formed in a peri region). A conductive layer for a floating gate is formed. Isolation trenches are formed by performing an etch process. Isolation layers are formed within the trenches and a dielectric layer is formed on a surface of the isolation layers and the conductive layer for the floating gate. A conductive layer for a control gate is formed on the dielectric layer. A hard mask layer for a gate patterning process and photoresist patterns are then formed. The hard mask layer is patterned along the photoresist patterns. The conductive layer for the control gate, the dielectric layer, the conductive layer for the floating gate, and a tunnel dielectric layer (a gate dielectric layer) are sequentially patterned along the patterned hard mask layer patterns.
However, as the degree of integration of semiconductor memory devices increases, the distance between the floating gates is further narrowed, which may cause a disturbance phenomenon between memory cells.